import java.util.Scanner;
public class Task13 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int x = sc.nextInt();
		int currentMax = Integer.MIN_VALUE;
		if (x < 0){
			currentMax = x;
		}
		
		while(x != 0){                        //Task not specified when to stop
			x = sc.nextInt();
			if (x < 0 && x > currentMax){
				currentMax = x;
			}
		}
		
		if (currentMax > 0){
			System.out.println("No negative number entered");
		}else {
			System.out.println(currentMax);
		}
		
		sc.close();
	}

}
